This invention concerns in general a floating cleaner head arrangement, and in particular an automatically adjustable floating cleaner head for use with a self-propelled front wheel drive floor cleaning apparatus, such as an upright vacuum cleaner.
Certain types of floor cleaning devices utilize cleaner heads which typically have vacuum nozzle areas located on the underside thereof adjacent a floor to be cleaned. As is generally known in the art, optimum nozzle height elevations above the floor to be cleaned are desirable to obtain maximum air flow through the nozzle, which flow is of course directly related to the cleaning performance of the machine. Since modern floor coverings can have various pile heights, ranging anywhere from low pile or bare floor to plush to shag, it is generally known to vary the chassis elevation so as to locate the vacuum nozzle areas a particular level above the surface to be cleaned depending on the particular type of carpet or floor covering.
One example of a cleaner head which may be adjusted for various carpet pile heights or thicknesses is illustrated by U.S. Pat. 4,342,132, issued to Fromknecht on Aug. 3, 1982, and commonly assigned with the present application. Fromknecht has a rearwardly located pile height foot or plate 40 for automatically sensing and indicating the pile height and density. Sensor foot 40 is connected via a cable with an indicator assembly 50 so that a user may perceive the sensed pile height and select a nozzle height accordingly. The user may then rotate a knob 34 to manually vary the nozzle height by adjusting the height of rear wheels 30.
Another example of a suction cleaner, and for which the nozzle thereof is more automatically maintained at a correct height, is disclosed by U.S. Pat. No. 2,244,132, issued to Charles H. Taylor on Jun. 3, 1941. Pile height sensing wheels are used to automatically influence the height of forwardly arranged cleaner supporting wheels, which serves to in turn influence the brush and nozzle height. In the Taylor mechanism, the supporting wheel height is influenced in the same direction as is the pile height sensing wheel.
Neither of the foregoing exemplary patents are directed to self-propelled units. Typically, self-propelled cleaners have rotatably driven drive wheels which are located generally rearwardly on the cleaner head. Several drawbacks arise with such an arrangement. For example, to transport the cleaner from room to room, in the case of an upright vacuum cleaner the cleaner is tipped back onto its rear wheels for transportation. If the rear wheels are adapted to be driven, such transport operation requires inclusion of a neutral clutch position for the driven rear wheels so that they will freely rotate during transport. Otherwise, movement of the unit would tend to be difficult if not impossible since rotation of the wheels with the drive motor therefor turned off would require overcoming friction within the clutches and gears of its transmission system.
Another drawback of typical prior self-propelled units is that the propelling force obtained with the drive wheels thereof is diminished in general as the height of the carpet pile to be cleaned increases. Without adjustment of such propelling force to compensate for varying characteristics of different floor surfaces, unsatisfactory performance of the selfpropelled feature can occur.